>> totally different situation, but from a medical point of view, if it's a foreign object in there, you got to get it out and you worry about infection. >> brian: you hear the little kid with his dad saying, i can't hear, i can't hear. i'm wondering, anyone near the explosion, was it loud enough where people's hearing, like in boston, was going to be affected? >> in both cases, you're going to hear about that, head trauma that you don't hear about initially, concussions you don't hear about initially. ear drums that are blown out you don't hear about initially, and ringing in the ears. when you're near an explosion, that's the number one thing you're going to see, people having ringing in the ears or loss of hearing. it can either be temporary or it can last for quite some time. >> gretchen: what about breathing in? we're talk being these types of fumes and toxins, who is in danger and mo who is not? >> it all depends on how close you are to this. anhydrous ammonia, you need at least 100 parts per million to be a major irritant with the lungs. again, this particular chemical sucks the water out of the tissues. so right i way you treat people with oxygen and with air. the more oxygen you can give into the lungs, the better.